The electrifying film A Streetcar Named Desire, directed in 1951 by Elia Kazan and based on Tennessee Williams' 1947 play, tells the feverish story of the pathetic mental and emotional demise of a determined, yet fragile, repressed and delicate Southern lady, Blanche, sensitively portrayed by Vivien Leigh, born to a once-wealthy family of Mississippi planters. Her impoverished, tragic downfall in the squalid, cramped and tawdry French Quarter one-bedroom apartment of her married sister, Stella (Kim Hunter), and animalistic brother-in-law (Stanley, Marlon Brando) is at the hands of savage, brutal forces in modern society. In her search for refuge, she finds that her sister lives (approvingly) with drunkenness, violence, lust, and ignorance.
Set in New Orleans in the years immediately following World War II, the film opens with the arrival of a train and a pretentious southern belle Blanche DuBois, who has taken the train to the city. As a joyous wedding party runs by in the station, Blanche appears like an apparition or angel out of a cloud of steam emitted by the train engine, as she carries her battered suitcase. Blanche is frail and in a neurotic emotional state, a faded-beauty with ragged, bleached hair and superficial, genteel Southern propriety. In her very first lines, she expresses her delusionary confusion to a young sailor, mentioning three streetcar stops--Desire, Cemeteries, Elysian Fields--that symbolize her desperate situation. She has come as a result of her sordid "desires" to the last stop available to her.
Blanche finds herself living emotionally in an era which has not only ended but has long since passed. She was raised to be 'merely' attractive, gracious well-groomed and to find a husband; the quintessential flirtatious "Southern Belle." The play and subsequent movie present her as unprepared for the post-war world at large, well into middle-age and unmarried. This is what is meant by "decorative." That she is described as a "fungus" reflects her neediness and tendency to cling. She is also, ultimately, poisonous to those around her, including Stella, Stanley, and her finally disillusioned suitor, Mitch (Karl Malden).
She is a "doomed dinosaur" in that she is without options, without the skills to survive, emotionally and financially, and with a tendency to live/escape in the past without confronting her own reality.